A scenario is one merger put to one set of markets: who is buying whom, on which data, measured how. You set it up in the pane on the left of the Scenarios page, run it, and Sloc works out the combined share, rank and concentration in every market at once. Save it and you can come back to it, or run the next variant alongside it.

Before you start, your markets need to be prepared and a subset to analyse created - see how to explore your market structure and create subsets.

Step 1 - Choose the subset to analyse

Subset to analyse sets which markets the scenario covers. Subsets are grouped by the data version they belong to, so picking one also picks the figures the analysis runs on. Underneath, Sloc shows what's in it - geographies, products and companies.

Step 2 - Name the merging parties

Choose the Acquirer, then one or more Target(s). Only companies that appear in the chosen subset are listed, and the acquirer drops out of the target list. Add every party to the transaction: Sloc treats them as a single merged entity and measures the increment they bring to each market.

Step 3 - Choose the concentration metric

Pick the metric shares are measured on under Concentration metric. The list holds the metrics your data actually has, so it's revenue unless you imported volume or another metric alongside it.

Click Analyse markets. The button says how many markets will be analysed, and results appear on the right when it finishes.

Step 4 - Save the scenario

Until you save it, the scenario is titled Unsaved scenario. Click the save icon at the top right, give it a name and a description, and click Save. Use the description to record what the scenario represents - "Full overlap, no divestments" tells your team far more than "Scenario 2".

Saved scenarios keep their results, so anyone on the project can open one and see the same numbers without re-running it.

Opening, renaming and starting again

Next to the scenario name, the folder opens a saved scenario and the reset icon clears the pane so you can start a new one. The pencil appears once a scenario is saved, for renaming it and editing its description. At the top right, the save icon saves your changes and the download icon exports the results.

The Open scenario window lists the scenarios saved in the project, with the data version, subset, parties and metrics each was run on, and when it was last analysed. The one you're in is marked Active. Use Show scenarios from to look at another data version's scenarios, and the bin to delete one you no longer need.

Pro tips

• Save a scenario before you start changing it. Running variants - a different target, a narrower subset - as separate saved scenarios means you can compare them later rather than rebuilding them.

• If a company you expect isn't in the acquirer or target list, it isn't in the subset. Check the subset on the Subsets page rather than the scenario.

• Changing the subset or the parties means the results no longer match the pane - re-run the analysis before reading them.

• Once it's run, see how to read your Concentrate results for what the numbers and the risk colours mean.